An "opponens" muscle is one which passes from the bones of the wrist to one or other of the bones of the middle of the hand called metacarpals, and the opponens pollicis passes of course, as its name implies, to the metacarpal of the pollex or thumb.

Though the foot of man is furnished with many muscles, like the hand, yet not one of the toes is provided with an "opponens" or muscle, passing from the bones of the ankle to one or other of the bones of the middle of the foot, which latter are called metatarsals.

A child who sits in front of video games and only works out his opponens pollicis muscles† is going to be in far worse shape than the kid who plays tag, jumps all over the playground, creates a jungle gym out of couch pillows, and is enrolled in the local gymnastics class.

In addition to very numerous other muscles on both surfaces, every one of the toes is provided with a separate opponens muscle, each having a muscle which passes from the bones of the ankle to its middle foot bone or metatarsal.